The purpose of this study was to test the validity of a new computerized task to assess children's cognitive problem-solving skills using the brain event-related potentials. This event-related potential-computerized cognitive problem-solving task does not require a child to give a verbal or motor (ie, pointing) response. The event-related potential waveforms were recorded from 20 typically developing children. Two nonverbal, problem-solving tasks (tasks 1 and 2) were developed for each of two age groups (5 and 6 years). For each task, single pictures, taken from an existing standardized test of nonverbal problem solving, were individually and sequentially presented on a computer screen. One of the seven pictures was classified as incongruent or outside category; it did not belong with the other pictures. As predicted, the event-related potential amplitudes were significantly larger to the outside- versus within-category pictures. This effect was found for tasks 1 and 2 for the 5- and 6-year-old children. Children as young as 5 years of age reliably exhibit brain activity, which can be used to infer cognitive problem-solving skill. This assessment paradigm may eventually serve as a clinically useful adjunct to a thorough neurologic and neurodevelopmental assessment of selected pediatric populations, such as those presenting with moderate-severe cerebral palsy whose expressive language and motor skills are notably impaired. (J Child Neurol 2001;16:325-332).